| Standard label: | Loan Commitments, Policy [Policy Text Block] |
| Name: | us-gaap:LoanCommitmentsPolicy |
| Documentation: | Disclosure of accounting policy for loan commitments accounted for as derivatives, including the methods and assumptions used to estimate fair value and any associated hedging strategies. |
| Object type: | cm:Level2TextBlock |
| Data type: | Text Block (HTML) (nonnum:textBlockItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:LoanCommitmentsPolicy |
| Label | Role | Language |
| Loan Commitments, Policy [Policy Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 235 10 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 815 10 S99 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 815 |
| FASB Accounting Standards Codification 815 10 S99 1 (SAB Topic 5.DD) | http://fasb.org/us-gaap/role/ref/legacyRef | 815 |